PIEZO Ion Channels in Cardiovascular Functions and Diseases.

The cardiovascular system provides blood supply throughout the body and as such is perpetually applying mechanical forces to cells and tissues. Thus, this system is primed with mechanosensory structures that respond and adapt to changes in mechanical stimuli. Since their discovery in 2010, PIEZO ion channels have dominated the field of mechanobiology. These have been proposed as the long-sought-after mechanosensitive excitatory channels involved in touch and proprioception in mammals. However, more and more pieces of evidence point to the importance of PIEZO channels in cardiovascular activities and disease development. PIEZO channel-related cardiac functions include transducing hemodynamic forces in endothelial and vascular cells, red blood cell homeostasis, platelet aggregation, and arterial blood pressure regulation, among others. PIEZO channels contribute to pathological conditions including cardiac hypertrophy and pulmonary hypertension and congenital syndromes such as generalized lymphatic dysplasia and xerocytosis. In this review, we highlight recent advances in understanding the role of PIEZO channels in cardiovascular functions and diseases. Achievements in this quickly expanding field should open a new road for efficient control of PIEZO-related diseases in cardiovascular functions.

Transient erythroblastopenia due to a GATA1 variant in an infant female.

Diamond-Blackfan anemia (DBA) is a congenital anemia with erythroid cell aplasia. Most of the causative genes are ribosomal proteins. GATA1, a hematopoietic master transcription factor required for erythropoiesis, also causes DBA. GATA1 is located on Xp11.23; therefore, DBA develops only in males in an X-linked inheritance pattern. Here, we report a case of transient erythroblastopenia and moderate anemia in a female newborn infant with a de novo GATA1 variant. In this patient, increased methylation of the GATA1 wild-type allele was observed in erythroid cells. Skewed lyonization of GATA1 may cause mild transient erythroblastopenia in a female patient.

A novel missense variant in ATP11C is associated with reduced red blood cell phosphatidylserine flippase activity and mild hereditary hemolytic anemia.

Adenosine Triphosphatase (ATPase) Phospholipid Transporting 11C gene (ATP11C) encodes the major phosphatidylserine (PS) flippase in human red blood cells (RBCs). Flippases actively transport phospholipids (e.g., PS) from the outer to the inner leaflet to establish and maintain phospholipid asymmetry of the lipid bilayer of cell membranes. This asymmetry is crucial for survival since externalized PS triggers phagocytosis by splenic macrophages. Here we report on pathophysiological consequences of decreased flippase activity, prompted by a patient with hemolytic anemia and hemizygosity for a novel c.2365C > T p.(Leu789Phe) missense variant in ATP11C. ATP11C protein expression was strongly reduced by 58% in patient-derived RBC ghosts. Furthermore, functional characterization showed only 26% PS flippase activity. These results were confirmed by recombinant mutant ATP11C protein expression in HEK293T cells, which was decreased to 27% compared to wild type, whereas PS-stimulated ATPase activity was decreased by 57%. Patient RBCs showed a mild increase in PS surface exposure when compared to control RBCs, which further increased in the most dense RBCs after RBC storage stress. The increase in PS was not due to higher global membrane content of PS or other phospholipids. In contrast, membrane lipid lateral distribution showed increased abundance of cholesterol-enriched domains in RBC low curvature areas. Finally, more dense RBCs and subtle changes in RBC morphology under flow hint toward alterations in flow behavior of ATP11C-deficient RBCs. Altogether, ATP11C deficiency is the likely cause of hemolytic anemia in our patient, thereby underlining the physiological role and relevance of this flippase in human RBCs.

Activation of pyruvate kinase as therapeutic option for rare hemolytic anemias: Shedding new light on an old enzyme.

Novel developments in therapies for various hereditary hemolytic anemias reflect the pivotal role of pyruvate kinase (PK), a key enzyme of glycolysis, in red blood cell (RBC) health. Without PK catalyzing one of the final steps of the Embden-Meyerhof pathway, there is no net yield of adenosine triphosphate (ATP) during glycolysis, the sole source of energy production required for proper RBC function and survival. In hereditary hemolytic anemias, RBC health is compromised and therefore lifespan is shortened. Although our knowledge on glycolysis in general and PK function in particular is solid, recent advances in genetic, molecular, biochemical, and metabolic aspects of hereditary anemias have improved our understanding of these diseases. These advances provide a rationale for targeting PK as therapeutic option in hereditary hemolytic anemias other than PK deficiency. This review summarizes the knowledge, rationale, (pre)clinical trials, and future advances of PK activators for this important group of rare diseases.

Congenital dyserythropoietic anemia type IV in the genetic era: A rare neonatal case report of rapid identification with a review of the literature.

Congenital dyserythropoietic anemia type IV (CDAIV) is a rare inherited hematological disorder, presenting with severe anemia due to altered erythropoiesis and hemolysis, with variable needs for recurrent transfusions. We present a case of a transfusion-dependent male newborn who presented at birth with severe hemolytic anemia, and required an intrauterine transfusion. Genetic testing rapidly identified a Kruppel-like factor 1 (KLF1) pathogenic variant (c.973G>A, p.E325K), known to be causative for CDAIV. This case highlights the advantages of next-generation sequencing testing for congenital hemolytic anemia: diagnostic speed, guidance on natural history, and optimized clinical management and anticipatory guidance for parents and clinicians. Additionally, we reviewed the literature for all CDAIV cases.

Glucose 6 Phosphate Isomerase Deficiency, a Rare Hemolytic Anemia Misdiagnosed as Hereditary Spherocytosis.

Hereditary hemolytic anemias are a heterogenous group of disorders that include membranopathies, enzymopathies, and hemoglobinopathies. Genetic testing is helpful in the diagnostic workup when the clinical and laboratory workup is not conclusive. Here, we present a case of a 21-month-old female who was initially diagnosed with hereditary spherocytosis based on the presence of a variant of unknown significance in the SPTB gene. Further genetic workup revealed a homozygous glucose 6 phosphate isomerase mutation and the patient was ultimately diagnosed with glucose 6 phosphate isomerase deficiency.

Mechanosensitive Pannexin 1 Activity Is Modulated by Stomatin in Human Red Blood Cells.

Pannexin 1 (PANX1) was proposed to drive ATP release from red blood cells (RBCs) in response to stress conditions. Stomatin, a membrane protein regulating mechanosensitive channels, has been proposed to modulate PANX1 activity in non-erythroid cells. To determine whether stomatin modulates PANX1 activity in an erythroid context, we have (i) assessed the in situ stomatin-PANX1 interaction in RBCs, (ii) measured PANX1-stimulated activity in RBCs expressing stomatin or from OverHydrated Hereditary Stomatocytosis (OHSt) patients lacking stomatin, and in erythroid K562 cells invalidated for stomatin. Proximity Ligation Assay coupled with flow imaging shows 27.09% and 6.13% positive events in control and OHSt RBCs, respectively. The uptake of dyes 5(6)-Carboxyfluorescein (CF) and TO-PRO-3 was used to evaluate PANX1 activity. RBC permeability for CF is 34% and 11.8% in control and OHSt RBCs, respectively. PANX1 permeability for TO-PRO-3 is 35.72% and 18.42% in K562 stom+ and stom- clones, respectively. These results suggest an interaction between PANX1 and stomatin in human RBCs and show a significant defect in PANX1 activity in the absence of stomatin. Based on these results, we propose that stomatin plays a major role in opening the PANX1 pore by being involved in a caspase-independent lifting of autoinhibition.

Morbilidad y mortalidad de 599 pacientes con drepanocitosis en el Instituto de Hematología e Inmunología / Morbidity and mortality of 599 sickle cell disease patients in the Institute of Hematology and Immunology

Introducción: La drepanocitosis es la anemia hemolítica congénita más común del mundo. Entre el 5 y 15 por ciento de la población mundial es portadora de la hemoglobina S y en Cuba, la frecuencia es de 3,08 por ciento, lo que representa un problema de salud pública. Objetivo: Caracterizar el cuadro clínico, el perfil hematológico y la probabilidad de supervivencia de los pacientes con drepanocitosis en el Instituto de Hematología e Inmunología. Método: Se realizó estudio descriptivo, longitudinal y retrospectivo, que incluyó todos los enfermos seguidos, al menos dos años, en la institución, entre enero de 1973 y diciembre del 2009. Resultados: Se incluyeron 599 pacientes (285 masculinos), 439 SS/Sβ0tal y 160 SC/Sβ+tal. El seguimiento medio fue de 17,6±9,5 años. Predominaron los pacientes entre 20 y 59 años. Los eventos clínicos más frecuentes fueron las crisis vasoclusivas dolorosas, las infecciones, el síndrome torácico agudo y las complicaciones hepáticas. Los valores de reticulocitos, plaquetas, leucocitos y hemoglobina fetal fueron significativamente mayores en los pacientes SS/Sβ0tal; no así la hemoglobina total que fue mayor en los SC/Sβ+tal. La probabilidad de supervivencia global de los pacientes a los 45 años fue de 69 por ciento. Los accidentes vasculares encefálicos (17,5 por ciento), las complicaciones hepáticas (17,5 por ciento) y las cardíacas (14,28 por ciento) fueron las principales causas de muerte. Conclusiones: La distribución demográfica y por hemoglobinopatías, el cuadro clínico, y el perfil hematológico fueron similares a los encontrados en pacientes de otras regiones geográficas, excepto la frecuencia de complicaciones hepáticas que fue mayor. La probabilidad de supervivencia fue similar con los mejores centros de atención en el mundo(AU)

Introduction: Sickle cell disease is the most common congenital hemolytic anemia in the world. Between 5 to 15 percent of the world population is a carrier of hemoglobin S and in Cuba, the frequency is 3.08 percent, which represents a public health problem. Objective: To characterize the clinical picture, the hematological profile, and the probability of survival of patients with sickle cell disease at the Institute of Hematology and Immunology. Method: A descriptive, longitudinal and retrospective study was carried out, which included all patients followed up for at least two years at the institution between January 1973 and December 2009. Results: 599 patients (285 male), 439 SS/Sβ0tal and 160 SC/Sβ+tal, were included. The mean follow-up was 17.6±9.5 years. Patients between 20 and 59 years old predominated. The most frequent clinical events were painful vasocclusive crises, infections, acute chest syndrome, and liver complications. The reticulocytes, platelets, leukocytes and fetal hemoglobin values ​​were significantly higher in the SS/Sβ0tal patients, but not the total hemoglobin, which was higher in the SC/Sβ+tal. The overall survival probability of patients at 45 years was 70 percent. Stroke (17.5 percent), liver complications (17.5 percent), and cardiac complications (14.28 percent) were the main causes of death. Conclusions: The demographic distribution and by hemoglobinopathies, the clinical events, and the hematological profile were similar to those found in patients from other geographic regions, except the frequency of liver complications, which was higher. The probability of survival was comparable with the best care centers in the world(AU)

First report of successful treatment for hemoglobin Bristol-Alesha by hemopoietic stem cell transplantation.

HBB gene mutations lead to many kinds of diseases, of which, except for the two most common diseases of thalassemia and sickle cell anemia, rare kinds of hemolytic anemia, such as hemoglobin Bristol-Alesha, are rarely reported, no ideal treatment in clinic. A child suffered from chronic recurrent hemolytic attacks and the related genes of hereditary hemolytic anemia were detected on her. Hematopoietic stem cell transplantation was conducted in the treatment of the patient. The patient was diagnosed as hemoglobin Bristol-Alesha and achieved complete recovery after hematopoietic stem cell transplantation. For Bristol-Alesha, without characteristic clinical manifestation and specific biochemical examination, diagnosis is dependent on the gene mutation detection and hematopoietic stem cell transplantation is an effective and curable method.

Acute human parvovirus B19 infection triggers immune-mediated transient bone marrow failure syndrome, extreme direct hyperbilirubinaemia and acute hepatitis in patients with hereditary haemolytic anaemias: multicentre prospective pathophysiological study.

A total of 244 patients with hereditary haemolytic anaemias (HHA) were screened for acute symptomatic human parvovirus B19 infection (HPV-B19) in a prospective study. To assess the risks associated with HPV-B19 infection, patients were classified into Group I and Group II according to presence or absence (symptoms, signs and specific serology) of acute HPV-B19 infection respectively. In all, 131 (53·7%) patients had ß-thalassaemia, 75 (30·7%) hereditary spherocytosis (HS), 27 (11·1%) sickle cell anaemia (SCA) and 11 (4·5%) glucose-6-phosphate dehydrogenase (G6PD) deficiency. Of 33 (13·5%) patients who presented with symptomatic HPV-B19 infection, 19 (57·5%) had HS, nine (27·3%) had ß-thalassaemia and five (15·2%) had SCA. In Group I, there were significant differences in the mean white blood cell, red blood cell and platelet counts, haemoglobin concentration, total bilirubin (TB), alanine aminotransferase, aspartate aminotransferase and serum creatinine (all P < 0·001) compared to Group II. In all, 27 (81·8%) patients had arthropathy and bone marrow failure (BMF); 13 (39·4%) had acute kidney injury (AKI), more in SCA (80%); and 12 (36·4%) patients had hepatitis, more in HS (66·8%). Five (15·2%) patients with HS had BMF, AKI, nervous system involvement and extreme hyperbilirubinaemia (TB range 26·3-84·7 mg/dl). Five (15·2%) patients had haemophagocytic syndrome. Two patients with HS combined with Type-I autoimmune hepatitis presented with transient BMF. Complete recovery or stabilisation was noted at 12 months in every patient except for one patient with SCA who died during the infection. HPV-B19 must be suspected and screened in patients with HHA with typical and atypical presentations with careful follow-up.

Screening tools for hereditary hemolytic anemia: new concepts and strategies.

INTRODUCTION: Hereditary hemolytic anemias are a group of rare and heterogeneous disorders due to abnormalities in structure, metabolism, and transport functions of erythrocytes; they may overlap in clinical and hematological features making differential diagnosis difficult, particularly in mild and atypical forms. AREAS COVERED: In the present review, the main tools currently adopted in routine hematologic investigation for the diagnosis of hereditary hemolytic anemias are described, together with the new diagnostic approaches that are being to be developed in the next future. Available recommendations in this field together with a systematic review through MEDLINE, EMBASE, and PubMED for publications in English from 2000 to 2020 in regards to diagnostic aspects of hereditary hemolytic anemias have been considered. EXPERT OPINION: The recent development of specific molecules and treatments for hereditary hemolytic anemias and the increased interest in translational research raised the attention on differential diagnosis and the demand for novel diagnostic assays and devices. Automatic blood cell analyzers, omic-approaches including NGS technologies, and development of new automated tools based on artificial neural networks definitely represent the future strategies in this field.

Hemolysis and Neurologic Impairment in PAMI Syndrome: Novel Characteristics of an Elusive Disease.

PSTPIP1-associated myeloid-related proteinemia inflammatory (PAMI) syndrome is a rare early-onset autoinflammatory disease associated with various hematologic findings, including chronic neutropenia and pancytopenia. We report a unique case of PAMI syndrome in a toddler with transfusion-dependent hemolytic anemia, hepatosplenomegaly, failure to thrive, developmental delay, and multiple malformations. Because of acute inflammatory-driven decompensation, anakinra was started with dramatic improvement of both the hematologic and neurologic involvement. A customized next-generation sequencing panel later identified a de novo pathogenic variant in the PSTPIP1 gene, confirming the diagnosis. Our case illustrates the broad spectrum of phenotypes associated with PAMI syndrome, which should be considered in any case of unexplained cytopenias associated with autoinflammatory stigmata. It is also one of the few reports of neurologic involvement in PSTPIP1-associated inflammatory diseases. Increased awareness of this rare disease and early performance of genetic testing can correctly diagnose PAMI syndrome and prevent disease complications.

Infantile Pyknocytosis in a Premature Dichorionic Diamniotic Twin.

Infantile pyknocytosis is a rare and self-limiting cause of hemolytic anemia in neonates. It can result in severe anemia and hyperbilirubinemia. The pathogenesis is unknown: a genetic origin has been discussed; however, based on the current literature it is not clear which genetic mutations should be considered. We present a case of a premature twin, in whom genetic screening was performed. Genetic mutations in 46 genes associated with hereditary hemolytic anemia and dyserythropoietic anemia were tested. No mutations were found. In infantile pyknocytosis, a genetic defect in these genes is unlikely.

Diagnóstico diferencial de las anemias hemolíticas / Differential diagnosis of hemolytic anemias

Introducción: El término hemólisis hace referencia a la destrucción de los eritrocitos y ocurre en un amplio rango de condiciones clínicas fisiológicas y patológicas. Es empleado para definir situaciones en la que la vida media de los eritrocitos está disminuida por causas mecánicas, tóxicas, autoinmunes o infecciosas. Objetivo: Describir los principales marcadores de hemólisis que se encuentran variablemente alterados en las diferentes formas de anemias hemolíticas. Métodos: Se realizó una revisión de la literatura, en inglés y español, a través del sitio web PubMed y el motor de búsqueda Google Académico de artículos publicados en los últimos 10 años. Se hizo un análisis y resumen de la información. Análisis y síntesis de la información: La hemoglobina es el marcador más directo de la gravedad clínica en las enfermedades hemolíticas. Sus valores pueden estar muy próximos a los valores de referencia en las formas ligeras (Hb > 100 g/L) o significativamente reducidos en las moderadas (Hb entre 80-100 g/L), graves (Hb entre 60-80 g/L) y muy graves (Hb < 60 g/L). Sin embargo, existen otros marcadores esenciales para diferenciar las formas de presentación aguda y crónica, la hemólisis extravascular de la intravascular y la presencia de signos extrahematológicos tales como: los reticulocitos y esquistocitos, la deshidrogenasa láctica, la haptoglobina, la bilirrubina, la ferritina y la hemosiderinuria. Conclusiones: Los parámetros hemolíticos pueden estar diferencialmente alterados en varias condiciones lo cual ayuda en la realización del diagnóstico diferencial de las anemias hemolíticas(AU)

Introduction: The term hemolysis refers to the destruction of erythrocytes, a process occurring in a wide range of physiological and pathological clinical conditions. The term is used to define situations in which mean erythrocyte lifespan is reduced due to mechanical, toxic, autoimmune or infectious causes. Objective: Describe the main markers of hemolysis found to be variably altered in the different forms of hemolytic anemias. Methods: A review was conducted of the literature about the topic published in English and Spanish in the website PubMed and the search engine Google Scholar in the last 10 years. Data were analyzed and summarized. Data analysis and synthesis: Hemoglobin is the most direct marker of clinical severity in hemolytic diseases. Its values may be very close to reference levels in mild disease (Hb > 100 g/l), whereas they will be significantly reduced in moderate (Hb 80-100 g/l), severe (Hb 60-80 g/l) and very severe disease (Hb < 60 g/l). However, other markers are also essential to distinguish acute from chronic presentation, extravascular from intravascular hemolysis, and the presence of extrahematological signs such as reticulocytes and schistocytes, lactate dehydrogenase, haptoglobin, bilirubin, ferritin and hemosiderinuria. Conclusions: Differentially altered hemolytic parameters may be found in several conditions, which makes them useful for the differential diagnosis of hemolytic anemias(AU)

Heme oxygenase-1 deficiency presenting with interstitial lung disease and hemophagocytic flares.

BACKGROUND: Heme oxygenase-1 (HMOX1) catalyzes the metabolism of heme into carbon monoxide, ferrous iron, and biliverdin. Through biliverdin reductase, biliverdin becomes bilirubin. HMOX1-deficiency is a rare autosomal recessive disorder with hallmark features of direct antibody negative hemolytic anemia with normal bilirubin, hyperinflammation and features similar to macrophage activation syndrome. Clinical findings have included asplenia, nephritis, hepatitis, and vasculitis. Pulmonary features and evaluation of the immune response have been limited. CASE PRESENTATION: We present a young boy who presented with chronic respiratory failure due to nonspecific interstitial pneumonia following a chronic history of infection-triggered recurrent hyperinflammatory flares. Episodes included hemolysis without hyperbilirubinemia, immunodeficiency, hepatomegaly with mild transaminitis, asplenia, leukocytosis, thrombocytosis, joint pain and features of macrophage activation with negative autoimmune serologies. Lung biopsy revealed cholesterol granulomas. He was found post-mortem by whole exome sequencing to have a compound heterozygous paternal frame shift a paternal frame shift HMOX1 c.264_269delCTGG (p.L89Sfs*24) and maternal splice donor HMOX1 (c.636 + 2 T > A) consistent with HMOX1 deficiency. Western blot analysis confirmed lack of HMOX1 protein upon oxidant stimulation of the patient cells. CONCLUSIONS: Here, we describe a phenotype expansion for HMOX1-deficiency to include not only asplenia and hepatomegaly, but also interstitial lung disease with cholesterol granulomas and inflammatory flares with hemophagocytosis present in the bone marrow.